All the central locking is controlled by the Body Control Unit so the first thing to do really is to get a wiring diagram and check out the continuity of the wiring to/from the various components that are at fault. A door lock fault could well be a broken wire in the body/door hinge area.
Of course if you can get hold of another BCU and swap it over that'd be a quicker check to see if this is generating your faults. It is the common denominator.
